Ruala is contesting the elections against two opponents - Robert Romawia Royte, an independent candidate sponsored by the eight-party United Democratic Alliance (UDF) and M Lalmanzuala of the Aam Aadmi Party (AAP).
The veteran Congressman first contested the Lok Sabha polls from Mizoram on Congress ticket in 1977 but lost to Dr R Rothuama of People's Conference by a margin of 16,006 in a four-cornered contest.
However, he won the 2009 Lok Sabha elections by defeating his nearest rival Dr H. Lallungmuana, an independent candidate sponsored by the opposition Mizo National Front (MNF) and the Mizoram People's Conference (MPC) by a margin of 1,08,955 votes, the highest ever in the electoral history of the state.
Born in 1936, he graduated from Shillong's St. Edmund's College in 1964 and joined the Congress party in 1968.
He became member of the Mizo District Council as a nominated member in 1970 and became Executive Member looking after Forest and Revenue departments.
After being elected from Tlungvel seat in the Assembly polls in 1978 and 1979, he won the assembly by-poll in 1984 from North Vanlaiphai seat and was inducted in the ministry headed by chief minister Lal Thanhawla.
He was re-elected from North Vanlaiphai seat in 1989 and 1993 assembly polls and continued as a senior cabinet minister till 1998 when the Congress was routed by the MNF in the state assembly polls.
Ruala who has an image of being a clean politician is poorest among the three candidates in the fray with Rs 5 lakh in hand.
He also has Rs 41,53,421.83 and Rs 2,15,80,000 movable and immovable property respectively.